Platinum nanobubbles having a uniform shell thickness of 20 nm with average outer diameters of 150, 320, and 420 nm have been synthesized readily by etching the silica cores of SiO2@Pt core-shell nanospheres and they have been found to catalyze the degradation of rhodamine B efficiently in the presence of KBH4 compared with SiO2@Pt core-shell nanospheres. The catalytic rate constant of the nanobubbles (0.030 min(-1)) with an activation energy of 10.7 kcal mol(-1) is larger by 23 times than that of the core-shell nanospheres with an activation energy of 30.5 kcal mol(-1). The catalytic activation energy and the entropy of activation obtained from the Arrhenius and the Eyring plots, respectively, have been found to increase with the size increase of platinum nanobubbles, due to the reduction of the nanoreactor confinement effect of platinum nanobubbles. The existence of a good compensation effect between activation energies and frequency factors has been evidenced to support that the catalytic degradation reaction takes place within the nanocavities of platinum nanocatalysts. (c) 2013 Elsevier B.V. All rights reserved.